Quantitative ultra-low temperature autoradiography, ultra-low temperature microdissection, and the intracellular reference phase technique are being used in studies of intracellular transport. These include studies of the permeability of the nuclear envelope, the nucleocytoplasmic distribution of solutes, and sorption-desorption processes. The experiments are in minimally distrubed cells, with large nuclei; especially the amphibian oocyte and the dipteran salivary gland cell.